The present invention relates to a process for producing pieces of jewelry from metal, particularly precious metal galvanoplastically, in that the metal is electrodeposited on an electrically conductive mould core having the spatial contour of the piece of jewelry and after reaching the desired coating thickness the mould core material is dissolved chemically or thermally from the hollow jewelry item. The invention also relates to pieces of jewelry produced by this process.
The use of galvanoplastics or electroforming has long been known in the manufacture of jewelry from precious metals. However, for a very long time the process has been limited to a few applications, particularly for the production of replicas of valuable originals or voluminous pieces of jewelry, in which a solid construction would lead to an excessive weight. It was disadvantageous that electrodeposition from gold baths was only possible with a relatively high carat value. However, of late, baths and technologies have been developed permitting the deposition in random carat values as from 8 carat. This has lead to a revival of this jewelry industry procedure so that now pieces of jewelry with a random shape and carat content can be produced galvanoplastically. The coating thickness is a few hundred microns, so that corresponding light pieces of jewelry can be manufactured, which, despite there hollow construction, have an adequate dimensional stability.
With regards to the technology it is pointed out that the mould core is produced in a conventional manner in a negative model or pattern of the piece of jewelry by slush moulding, the material in question being constituted by any random material which can be thermally or chemically liquefied or volatilized without the precious metal suffering. Apart from metals, in the case of materials which are not in themselves electrically conductive, such as e.g. waxes, they are coated in an electrically conductive manner, e.g. with metal. The separation of the core material from the precious metal body then takes place either thermally or chemically and in the deposited precious metal coating either an opening is provided or this is subsequently made to enable the core material to escape. In the case of metallically coated wax, this can optionally be dissolved out before hand and the then hollow mould core is used in the galvanic bath.
Due to the limited wall thickness, in many pieces of jewelry problems occur at points where there will be greater mechanical stressing during subsequent working or correct use. Although a hollow profile can be made adequately stable against tensile and bending stresses in the case of a correspondingly large wall thickness, a hollow profile with a limited wall thickness is e.g. sensitive to scouring or abrading repeated stressing, because the wall thickness is gradually worn away with the increasing period of use. Also when the hollow profile is used for mounting, guiding or fixing other parts, particularly moving parts, damage can occur. This can e.g. apply in the case of loops or eyes of pendants, for the rail, strip or rim of rings, for the connection parts of movable elements or fastenings on chains, bracelets or the like, as well as for brooches, supports, hooks, catches or the like.